Control circuit for electrical relays



CONTROL CIRCUIT FOR ELECTRICAL RELAYS Original Filed July 30, 1935 AT 2 I: n

. 2 4: B 2517? 7F H Closed mid ii siroke and B 15 L {15 B Full down.

15 B 15 4 C 851 F I INV TOR L Pew .Crcz 0 H15 ATTORNEY Patented June 20, 1939 UNITED STATES PATENT OFFICE CONTROL CIRCUIT FOR ELECTRICAL ELAYS Paul H. Crago, Wilkinsburg, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania 7 Claims. (01. -320) My invention relates to control circuits for electrical relays, and has for an object the provision of novel and improved control circuits for interlocking relays.

The present application is a division of my application filed July 30, 1935, Serial No. 33,839, for Railway signaling apparatus, now Patent No. 2,056,712 granted October 6, 1936.

I will describe two forms of apparatus embodying my invention, and will then point out the novel features thereof in claims.

In the accompanying drawing, Figs. 1 and 2 are diagrammatic views illustrating two forms of circuits and apparatus, each embodying my invention.

Similar reference characters refer to similar parts in each of the views.

Referring first to Fig. l, the reference characters I and la designate the rails of a stretch of railway track, which rails are divided by insulated joints 2 to form two track sections designated A and B, respectively, with their adjoining ends located at a highway intersection designated H. Each track section is provided with a track circuit including a source of current 3 connected across the rails at one end of the section, and a track relay desi nated TR having a prefix corresponding to the section to which it belongs and connected across the rails and la at the other end of the section. The highway signal S may be of any suitable type and is under the immediate control of the magnets Al and B! of the interlocking relay IR. This relay may be of any of the well-known types, such as, for example, the type disclosed in Patent No. 1,799,629, issued to William K. Lockhart and Thomas J. OMeara, April '7, 1931. Such interlocking relay is provided with two magnets, an armature for each magnet, and an interlocking mechanism between the armatures. When both magnets are energized the armatures are both raised to an attracted position. When either magnet is deenergized the associated armature is released and falls to a full down position and the interlocking mechanism is actuated to latch the other arma ture at an intermediate or mid-stroke position in the event the other magnet is subsequently deenergized. Each of the magnets Al and BI of relay IR is normally held energized over a circuit including the front contact of the associated track relay, in series with a resistor R2. of the magnets Al and BI when picked up excludes at its back contact 12 a portion of the winding of the associated track relay from the track circuit and in addition makes it necessary for all Each track circuit current to pass through the associated resistor RI. This is one of the usual expedients employed in a primary-secondary track relay combination to increase the release sensitivity of the primary or track relay.

Each of the magnets Al and Bi at its back contact I3 controls the signal S in the usual manner. It may be well to explain at this time that the back contacts H and I3 of each of the magnets Al and BI are closed when the armature of the associated magnet is the first to be released by the relay IR, but become latched in the open position if the armature associated with the other magnet of relay IR is first to be released. The back contact l2 of either magnet of this relay always closes when its magnet becomes deenergized; while the front contact ll of either magnet always closes when its magnet becomes energized.

I will now assume that a train moving toward the highway enters section A, thereby shunting current away from the track relay ATR. When relay ATR releases, its front contact opens the circuit for magnet Al of relay IR. When magnet Al releases, its back contact ll places a shunt around the associated resistor R2, thus preparing a pick-up circuit for magnet AI. Also, back contact 12, by closing, includes the formerly excluded portion of the winding of relay ATR in the track circuit, thereby preparing the pick-up circuit for relay ATR. Furthermore, magnet Al closes at back contact [3 a circuit through signal S, which signal accordingly operates as long as the section remains occupied.

When the train enters section B, track relay BTR also releases and at its front contact opens the circuit of magnet Bl. When magnet B! is deenergized and releases its armature, its back contact l2 closes and includes the entire winding of relay BTR in the respective track circuit, thereby preparing for pick-up of this relay when the train vacates section B. When the armature of magnet BI is released the back contacts II and I3 of magnet BI, however, do not close at this time as they have been latched in the open position because the armature of magnet B! is latched in its intermediate position by the prior release of the armature of magnet Al.

As the train vacates section A, the track relay ATR again picks up and at its front contact reestablishes a circuit for magnet Al. This circuit includes the closed back contact H of magnet Al and the associated resistor R2 in multiple. After a slight delay, magnet AI picks up, opening back contact II to include the associated resistor -.AI and BI to an undesirable value.

rent supplied to the winding of magnet BI is re 'duced by resistor R2 sufficiently to retard the pick-up time of this magnet in such a manner as substantially to offset the tendency for the pickup to be accelerated due to the reduction of the air gap between the magnet armature and core resulting from the mechanical latching of the armature of magnet B! in the intermediate position to hold contacts I l and I3 open, as previously explained.

Since the relationship between track relay BTR and interlocking relay IR is symmetrical with that existing between track relay ATR and relay IR, it will be apparent that the control of signal S will be the same irrespective of the direction from which a train approaches the intersection.

In Fig. 2, I have shown the circuits and apparatus of Fig. 1 modified by the addition of a connection between the front and back points of contact ll of magnets Al and Bi. The front point of contact H is employed in order to over come the tendency of resistor R2 to reduce the final level of energy in the windings of magnets The operation will be the same as described for Fig. 1, except that when magnets A! and Bi pick up, their front contacts Ii will again shunt out the associated resistors, R2, thereby restoring the energy being supplied to the relay to the value used for initially picking it up from its fully released position.

In Fig.2 I have also shown the signai S as being controlled through the medium'oi a repeater relay RE which is energized over flagman type front contacts l3 of magnets Al and BI to illustrate the form the invention will take when the current load of the signal S, or this signal plus other apparatus exceeds the capacity of the contacts available on the interlocking relay IR.

It will be understood; of course, that my present invention is not limited to apparatus for governing the operation of highway crossing signals, and the control circuits for interlocking relays here disclosed and claimed are useful where interlocking relays are employed for governing other circuits.

Although I have herein shown and described only two forms of apparatus embodying my invention,it is understood that various changes and modifications may' be made therein Within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is 1. In a control circuit for an interlocking relay provided with two windings and two armatures each armature having a fully released as well as anwintermediate positionbyvirture oi' the mechanical interlocking between the two armatures, means for picking up a particular one of the armatures of such relay from its fully released position within a fixed interval of time after a circuit is closed through the winding for said one armature, and means for also retarding-the pick-up...

of such armature from the intermediate position for substantially the same period of time when the circuit is closed through its winding.

2. In a control circuit for an interlocking relay having a pair of magnets, a first pick-up circuit for a particular one of the magnets of the relay including a back contact of such magnet, a secondpick-up circuit for said magnet including a resistor in multiple with said back contact, and a holding circuit for said magnet including a front contact of said magnet.

3. In combination with an interlocking relay provided with two windings and two armatures onearmature for each winding, a pick-up circuit for each winding each of which circuits includes a resistor, and meansassociated with each winding to shunt the resistor of the associated pick-up circuit and including a contact closed in the fully released position of the armature oi the winding.

4. In combination with an interlocking relay provided with two windings and two armatures one armature for .each winding, two resistors, a pick-up circuit for each winding, said pick-up circuits each including a current source and a different one of said resistors and each being efiective to create a predetermined energization of the associated Winding, and means associated with each pick-up circuit and including a contact closed only in the fully released position of the armature of the associated winding for shunting the.

' ing armatures one armature for each magnet,

two resistors, two normal energizing circuits one for each magnet and each circuit serially including the winding of the associated magnet and a different one of said resistors, two shunt paths one associated with each of said circuits and each including a back contact of the armature controlled by the magnet energized by the associated circuit, each said shunt path being eifective when the contact included therein is closed to shunt around the resistor of the associated circuit.

6. In combination, an interlocking relay provided with two magnets and two contact controlling armatures one armature for each magnet, an energizing circuit for each magnet including the winding-of the magnet and a resistor in series, a shunt path for each of said circm'ts including a full down contact of the armature controlled by the magnet energized by the associated circuit, each said path being eiiective when the associated contact is closed to short circuit the resistor of the associated circuit to efiect a substantially uniformpick-up period for the associated armature.

7. In combination; an interlocking relay having two windings and two contact controlling armatures one armature for each winding and Which armatures are mechanically interlocked to effect an attracted position, a mid position and a full down position for each armature; an energizing circuit for a particular one of said windings operative to supply current of a selected value to said one winding for moving the armature of the winding from its mid position to its attracted position, and means controlled by the armature of said one winding to change said energizing circuit to supply current greater than said selected value to move the armature from its full down position to its attracted position.

. PAUL H. .CRAGO; 

